I've been seeing lots of questions around this on the boards, and when I do I refer them to Chris Hernandez' awesome post (see below) on taking MOSS from a standalone setup to a farm one. The steps apply for both WSS and MOSS, just for WSS you don't have the Shared Services stuff. In a nutshell...
- Set up your target environment farm (remember, Advanced/Complete!)
- Use your SQL tools to backup the databases on the source server, and restore them to the target one
- Use the STSADM Command Line utility to attach the restored databases to the relevant areas
Even though his post is from '07, it's still valid, and has helped out a lot. Check out his detailed steps in the link below...enjoy! - M
Migrating Microsoft Office SharePoint Server (MOSS) from Standalone to Farm Install